Do Airport X-Rays Kill Microorganisms?

Airport security systems use X-ray technology to scan carry-on luggage and, in some cases, passengers themselves. The X-rays used in these systems are typically in the range of 140 to 160 kilovolt peak (KVP), which refers to the amount of penetration an X-ray makes. While X-rays can be harmful to living things, the doses used in airport security systems are considered very low. There is ongoing debate about whether these low doses of X-rays can cause harm to humans, particularly those who are more vulnerable to radiation, such as children. However, studies have shown that the radiation dose received by objects scanned by airport X-ray systems is usually 1 millirad or less, which is significantly lower than the average dose rate from background radiation.

Do X-rays in airports have enough energy to kill microorganisms?

X-ray systems are commonly used in airports to scan both carry-on and checked baggage. These systems emit low-energy waves and use either backscatter or millimetre wave technology to generate images. The former is more common in the US and is considered safe for all but the fastest film speeds.

The energy emitted by X-ray systems is not high enough to kill microorganisms. A study by the Public Health Agency of Canada and Health Canada found that low-to-medium energy X-ray radiation does not significantly reduce the viability of 11 different microorganisms, including bacteria, bacterial spores, yeast, and viruses.

The US Food and Drug Administration (FDA) is responsible for ensuring that manufacturers produce X-ray systems that do not pose a radiation safety hazard. The FDA has set a limit on radiation emissions, restricting the radiation emitted from a cabinet X-ray system to no more than 0.5 milliroentgens in one hour at any point five centimetres from the external surface. Most X-ray systems emit less than this limit.

Additionally, the average dose rate from background radiation is 360 millirads per year, while the radiation dose typically received by objects scanned by a cabinet X-ray system is 1 millirad or less. This further suggests that the energy emitted by X-ray systems in airports is not high enough to kill microorganisms.

What are the different types of X-ray scanners used in airports?

X-ray scanners are an essential component of airport security, helping to ensure the safety of passengers and staff. Here is an overview of the different types of X-ray scanners used in airports:

Dual-Energy X-ray Systems:

These systems are commonly used for screening carry-on luggage. They employ a single X-ray source with a range of 140 to 160 kilovolt peak (KVP), which determines the penetration ability of the X-rays. In this system, X-rays pass through a detector, a filter, and then another detector. The filter blocks lower-energy X-rays, allowing only high-energy X-rays to reach the second detector. This enhances the visibility of low-energy objects like organic materials, which are typically coloured orange on the display.

Millimeter Wave Scanners:

Millimeter wave scanners are used for body scanning and employ non-ionizing radiation in the form of low-level radio waves. They use two antennas that rotate around the body, creating a 3D image that is sent to a remote monitor. This technology does not use X-rays and does not contribute to a person's ionizing radiation dose. It is considered safe and releases far less energy than a cell phone.

Backscatter X-ray Machines:

Backscatter X-ray machines are used for body scanning and can detect weapons, explosives, or other threats hidden under clothing. They use very low-energy X-rays that are reflected back to the machine. The radiation exposure from these machines is minimal, comparable to the amount of cosmic radiation received during two minutes of flight.

Cabinet X-ray Systems:

Cabinet X-ray systems, also known as closed X-ray systems, are used for screening checked luggage and carry-on items. They have enclosed cabinets with thick walls and lead curtains at entry and exit points to prevent radiation from escaping. These machines must meet strict standards for radiation containment and are equipped with safety features like locks, warning lights, and labels.

CT Scanners:

CT scanners are not commonly mentioned in the context of airport security, but they are high-energy X-ray systems that can be used for examining checked baggage. They can damage photographic film, but electronic devices can safely pass through them.

How do X-ray scanners work?

X-ray scanners are used at airport security to check for dangerous goods and ensure that flights reach their destinations safely. They are used to build a picture of what's inside passengers' bags, allowing security staff to check for suspicious items.

X-ray scanners work by sending out X-rays, which are electromagnetic waves with high energy that can penetrate many materials. The X-rays pass through the bag and are then picked up by a detector. The detector then passes the X-rays on to a filter, which blocks out the lower-energy X-rays. The remaining high-energy X-rays hit a second detector.

By comparing the pick-ups of the two detectors, the machine can construct an image that shows the position of objects and their density. Different materials are shown in different colours: organic matter, such as wood, water, plastic, and textiles, are coloured orange; inorganic matter, such as metals, show up as blue; and when organic and inorganic substances overlap, they appear green on the screen, for example, tennis balls in a metal tube. The denser the substance or the thicker the layer of substance, the darker the item appears on the screen. Substances that are too dense for the radiation to penetrate appear black.

The Transportation Security Administration (TSA) in the United States typically uses a dual-energy X-ray system, which has a single X-ray source sending out X-rays in the range of 140 to 160 kilovolt peak (KVP). KVP refers to the amount of penetration an X-ray makes, so the higher the KVP, the further the X-ray penetrates.

In most X-ray scanners, two sources are used: one is suspended at the top, and the other stays at the side. This provides two different points of view of the same package, helping to identify objects that may be blocked from one side and eliminating the possibility of hiding contraband.

What are the potential health risks of X-ray scanners?

X-ray scanners, such as those used in airports, have potential health risks due to the emission of ionizing radiation. Ionizing radiation can cause damage to DNA, which may lead to cancer later in life. This damage occurs when high-energy wavelengths or particles penetrate tissue and interact with atoms, molecules, and cells in the body. The risks associated with X-ray exposure depend on various factors, including radiation dose, type of radiation, age, and the part of the body exposed.

X-ray scanners used in airport security typically operate within a range of 140 to 160 kilovolt peak (KVP). The higher the KVP, the greater the penetration of the X-ray. These scanners utilise a dual-energy X-ray system, employing a single X-ray source that emits X-rays through a detector, a filter, and then another detector. The X-rays that pass through the item are picked up by the second detector, which blocks out lower-energy X-rays, allowing only high-energy X-rays to create an image.

While the benefits of X-ray technology in medical imaging far outweigh the potential risks, there is still a slight increase in cancer risk associated with their use. This risk is estimated to be 0.4% in the United States, and it is higher in children. Additionally, exposure to high radiation levels can cause short-term side effects such as vomiting, bleeding, fainting, hair loss, and skin and hair loss.

To minimise the potential health risks of X-ray scanners, it is recommended to limit exposure and only use them when necessary. Keeping track of one's X-ray history and discussing the need for high-dose diagnostic imaging with a clinician are also important steps to reduce potential harm.

How do X-ray scanners impact privacy?

X-ray scanners have raised concerns about their impact on privacy, especially in the context of airport security screening. Here's how they impact privacy:

• Detailed Images: X-ray scanners used in airports can generate highly detailed images of individuals' bodies, revealing intimate details such as genitalia, breasts, buttocks, and prosthetics. This level of detail has been likened to a "virtual strip search" by some critics.
• Image Storage and Dissemination: While measures are in place to prevent the storage and dissemination of scanned images, there have been reports of tens of thousands of images being improperly saved and shared, raising concerns about the effectiveness of these safeguards.
• Religious and Cultural Sensitivities: The use of X-ray scanners has faced opposition from religious and cultural groups who consider them invasive and a violation of their beliefs and practices.
• Public Perception: The public's perception of X-ray scanners varies. While some may be willing to accept this technology for enhanced security, others may be uneasy about the level of detail revealed and the potential for privacy breaches.
• Privacy Safeguards: To address privacy concerns, authorities have implemented measures such as blurring faces, installing software to reduce the provocative nature of images, and separating security personnel from passengers to ensure they cannot be identified directly.
• Legal and Ethical Considerations: The use of X-ray scanners has sparked legal debates, with some arguing that they violate privacy laws, religious freedom, and video voyeurism prevention statutes.

While X-ray scanners can provide enhanced security, their impact on privacy has been a subject of debate and concern, leading to ongoing discussions about balancing security needs with individuals' rights to privacy and anonymity.

Frequently asked questions